A study conducted at Boston-based Beth Israel Deaconess Medical Center has produced promising results in Zika-infected mice dosed with a purified, inactive of the virus, The Guardian reports.
The researchers tested two versions of experimental vaccine, the first made of genetic material taken from the Zika virus circulating in the Brazilian outbreak. The second was made from an inactivated version of the virus found in Puerto Rico. Although the injection gave the mice complete immunity from the virus, that doesn't mean it can be easily converted into a human vaccine.
Lead researcher Dan Barouch, MD, PhD, told The Guardian that the trial is a significant step forward, but it's important to be cautious about extrapolating the results of an animal model to people.
"We were very surprised and quite impressed that a single shot of either one of these vaccines provided complete protection," Dr. Barouch said.
One concern the researchers must contend with, according to The Guardian, is recent research that showed a link between dengue virus and Zika, both of which circulate in similar parts of the world. Imperial College London researchers demonstrated that previous exposure to one could potentially worsen symptoms of the other. Because vaccines work by exposing an individual to an innocuous version of the virus, there's a risk that dengue infections could become harder to fight off for those living in areas where both are common.
The researchers are now investigating how long the vaccines remain effective in mice and whether a booster shot of the inactivated virus would extend protection.
"Taken together, our findings provide substantial optimism that the development of a safe and effective [Zika virus] vaccine for humans will likely be feasible," the authors concluded in the Nature paper.